In 1892 William Painter, founder of the present Crown Cork & Seal Company, was granted a patent for a beverage seal. Mr. Painter called this seal a crown because it resembled a crown of the type used by the nobility.
Natural cork disks were used in the early crowns. It was normal to have leaks in up to one percent of the closures. Later, composition cork come into use about 1915 and was an immediate success: This crown type was currently named “Standard Crown.” The original principle, the bottle finish and the means of applying the crown remained practically the same for 100 years.
An important modification, still in use, was introduced many years ago: A reduction of the cork disk's thickness from ⅛ inch to 1/16 inch, and consequently, a reduction of the height in the skirt wall from 0.262 inch (Standard Crown) to approximately 0.228 inch (named “Short Skirt”) was accomplished. There were also intermediate designs now forgotten.
Because the seal of composition cork is cut in disks, the lodging zone of the shell is alike and has a near cylindrical shape. During crowning there were practically no deformation of crowns in the zone between the seal surface of bottles and skirt wall of crowns, because it remained filled by the cork.
As shown in FIGS. 1A-1C, after introducing in 1955 the first commercial molded plastic liner by Bond Crown, a division of Continental Can Company, Inc. named “triple seal”, it was possible to affect a significant reduction in seal volume, using practically the whole material close to the seal surface. This construction has produced an absence of seal material in the junction of the crown top and the beginning of the skirt wall, just outside to the seal surface. As a consequence, during crowning, this zone is deformed, with tendency to take the shape of the finish bottle contour.
This stretching of crowns causes tilting of crowns (crimped sideways on bottle) and high friction on internal lacquer, breaking it and making possible that internal corrosion takes place later. Also there is an over damaging of serrations and wearing of the bottle finish, reducing the useful life of returnable bottles.
This utility model is intended to solve thereafter mentioned problems by its special and particular configuration: A curved portion between skirt's wall and crown top adapted to the same shape as the bottle finish mouth contour that, at the same time, allows a reduction of the original blanking diameter, producing more crowns per sheet.